The present invention relates to a bearing structure. The present invention more particularly relates to a bearing structure for an expansion joint system and an expansion joint system including the bearing structure.
An opening or gap is purposely provided between adjacent concrete structures for accommodating dimensional changes within the gap occurring as expansion and contraction due to temperature changes, shortening and creep of the concrete caused by prestressing, seismic cycling and vibration, deflections caused by live loads, and longitudinal forces caused by vehicular traffic. An expansion joint system is conventionally utilized to accommodate these movements in the vicinity of the gap.
Bridge constructions are especially subject to relative movement in response to occurrence of thermal changes, seismic events, and vehicle loads. This raises particular problems, because the movements occurring during such events are not predictable either with respect to the magnitude of the movements or with respect to the direction of the movements. In many instances, bridges have become unusable for significant periods of time, due to the fact that traffic cannot travel across damaged expansion joints. Gaps or openings in the bridge deck are provided for accommodating these movements, and expansion joint systems are often installed in the gap.
Prior art expansion joint systems include various types of bearings for absorbing loads applied to the expansion joint system and for supporting the various expansion joint system components. However, many of the bearings used in expansion joint systems cannot absorb the increased loads and rotations that are demanded by the roadway and bridge designs. Therefore, a need still exists in the art for an improved bearing structure that can accommodate increased loads and an expansion joint system including an improved bearing that can accommodate movements that occur in the vicinity of a gap having an expansion joint between two adjacent roadway sections, for example, movements that occur in longitudinal and transverse directions relative to the flow of traffic, and which are a result of thermal changes, seismic events, and deflections caused by vehicular loads.